The concerns raised by Drs Burnstein and Robin are of interest, and speak not only to our study,1 but also to clinical glaucoma care in general. What is the importance of IOP? What role does it play? Burnstein and Robin state, "The presence of glaucomatous damage of the optic nerve in the absence of elevated IOP has brought into question the role of IOP as a causative factor in the development of the disease."